Several applications are known in which electrical connections need to be provided underwater. Examples include a subsea installation for the production of hydrocarbons from a subsea well, in which different components of the subsea installation may need to be connected electrically. Such connections may for example comprise a connection from a topside installation, such as a floating or fixed platform, or from an onshore site to a subsea component, e. g. by an umbilical or a subsea cable. Other connections include electrical connections between different type of subsea equipment, such as a connection between a subsea transformer and subsea switchgear, electrical connections to a pump or a compressor or the like.
For providing an underwater electrical connection, wet-mateable connectors are known which can be mated underwater. Although such type of connectors are generally more complex than corresponding dry-mate connectors, which have to be mated above water, wet-mateable connectors have several advantages. Components of the subsea installation can for example be disconnected and can be retrieved for servicing or exchange, additional components may be connected to an existing subsea installation, electric connections can be provided to a subsea structure after installation thereof at the ocean floor, and the like.
A general problem with such subsea connectors is the corrosive character of seawater. Seawater generally causes corrosion and degradation of materials exposed thereto. Exposed surfaces are furthermore prone to the growth of organic material thereon, such as algae, bacteria and the like. Such marine growth can be detrimental to the functioning of the subsea connector.
Accordingly, in order to protect exposed surfaces when the connector parts are unmated (e.g. when a connector part is unplugged and not in use), it is known to use “dummy plugs” or “dummy receptacles” to which the connector part is mated. Components of the connector part, such as a pin, can thus be protected effectively from the surrounding seawater. Such dummy plug generally needs to include all features of a standard plug at its connecting section, but does not connect to a cable but only to a dummy gland, which isolates the pin from the metal works and which may be used for electrical testing. As such fully functional dummy plug may need to be provided for each un-mated connector part, significant costs can be incurred.
Furthermore, it is known to flush connector parts before mating by filtered seawater to remove debris, such as described in EP 2520757 A2. Even with such prior cleaning of the contact portions of the connector, the electrical contact provided by the connector may be degraded due to the exposure of the contact surfaces to seawater.
In particular at high voltages, e. g. voltages above 5,000 V, 10,000 V or even 30,000 V, even a minor degradation of the electrical contact provided by the connector may have significant consequences, such as a reduced lifetime of the connection, or even a failure in the connection. The same applies to optical connections, in which marine growth or debris may sincerely affect the quality of the connection or may even result in the connection not being established.
It is thus desirable to at least reduce the effects of seawater on a connection provided by such wet-mateable connector. It is desirable to provide a connection in a reliable and effective way. Furthermore, the complexity of the connector should not be increased significantly. Also, it is desirable that the connector parts remains operational over a relatively large number of mating/demating cycles and have a relatively long lifetime. It is in particular desirable to provide an improved connector for subsea use in a cost-efficient way.